RESUMEN
Yeast biomass from ethanol industry (YB) was evaluated as a biosorbent to 17α-ethinylestradiol (EE) alone and along with estrone (EST). This material is rich in sorption sites and has a good cost-benefit ratio, since it is an industrial residue largely produced (around 30 g for each liter of ethanol). A 2k-factorial design was carried out to evaluate the sorption capacity of YB for EE considering the variables pH, biosorbent dose (BD), and ionic strength (IS), at two hormone concentration (HC) levels. The best conditions assessed for individual EE adsorption (pH = 10, IS = 0.1 mol/L, and BD = 0.5 mg/L) were also established for adsorption carried out in the presence of EST. Individuals EE and EST experimental sorption capacities (SCexp) were, respectively, 24.50 ± 0.07 and 0.80 ± 0.07 mg/g, fairly similar to Qmax (EE, 21.41 ± 1.27 mg/g; EST, 0.93 ± 0.075 mg/g) from Langmuir model. The Freundlich model best fitted the experimental data for EE adsorption (r2 = 0.9925; χ2 = 0.5575). The study carried out in the presence of EST showed an associative/competitive sorption process between EE and EST, which may be explained by their similar chemical structures and organic carbon-water partition coefficients Koc.
